Grease



a soap,

Patented Aug. 20, 1.935

UNITED STAT-ES GREASE Arthur W. Burwell, Niagara Falls, N. Y., assignorto Alox Corporation, New York, N. Y., a corporation of New York NoDrawing. Application October '1, 1931,

Serial No. 567,527 r l 8 Claims. (01. 81- 9) This invention relates tolubricating greases and to a process for preparing the same.

By the expression lubricating grease is meant a semi-solid lubricantcomprising a mixture of such for instance as a calcium soap ora sodiumsoap made from tallow, and a lubricating oil, such for instance as amineral oil of medium viscosity, which mixture may or may not be anemulsion. According to their constitutions and uses, they are, knownvariously as cup greases", driving journal compounds, fiber greases,gear greases, axle greases, and by many other names.

Typical of such lubricating greases, and of the methods commonlyemployed in their manufacture, is the following:

To about 90 pounds of stearic acid (single pressed), or to an equivalentamount of good stearine or tallow, in a steam-jacketed kettle providedwith a stirrer, is added nearly a like quantity, say 100 pounds, ofsteam-refined cylinder stock, and the resulting mixture is agitateduntil a homogeneous mixture results. To this homogeneous mixture thereis then added suflicient caustic soda solution (say, 50% solution) tosaponify all the saponifiable constituents thereof, and the mixture isthen heated, with constant stirring, until not more than about 1% ofwater remains in the mass. The progress of the reaction is indicated bythe evolution of steam, and the heating temperature is so regulated thatthe reaction mixture does not boilv over. The resulting extremelyviscous, sometimes crumbly, mixture is then withdrawn into suitablecontainers in which it, upon cooling, solidifies. This product, aso-called driving ioumal compound", has a dark brown to black color, anda fibrous fracture, is sticky and harsh to the touch, and

may be "worked between the fingers to a rather stifibut slightly spongymass. It begins to flow readily at about 475 to 500 F.; at temperaturessubstantially below this flow point it does not readily yield lubricantfilms. In use, a cake of the material is placed in the "cellar of alocomotive driving journal upon a spring-actuated feeding device whichforces the cake against and through a perforated plate or coarse screen(e. g., one having openings from A; to inch) which plate or screen isimmediately under the bearing surface of the journal.

Lubricating greases similar to the above-described have variousdisadvantages, aside from that just noted, including chiefly a tendencyto leak or give up their contents of lubricating oil more readily thantheir contents of soap, with unctious rather the result that thepartially used cake or mass has a too-high soap content and an undulyhigh melting point so that the journal itself must be heated to stillhigher temperatures before the mass will feed properly and form aninterface.

It 'is the common practice to evaluate such greases on the basis of therelative value of their lubricating oil constituents, as it is commonlyunderstood that the lubricating value of the grease is dependent mainlyupon the oil therein: consequently in well made greases only high gradelubricating oil stocks commonly are employed.

I have found that the above, and other disadvantages may be .overcome,and that a very material economy may be secured, by preparinglubricating greases from lubricating oils and soaps of certain acidicmixtures obtained by the partial, liquid-phase, oxidation ofhydrocarbons of mineral origin. The'lubricating greases, embodying thepresent invention readily give off lubricant films at temperaturesmaterially below their flow points; do not leal-r" their lubricating oilcontents but persist as constant com-- positions; and are furthercharacterized by an than a sticky .feel, slipperiness, a conchoidalfracture, and a rubbery as opposed to fibrous structure.

As starting material for the preparation of the soaps employed inpreparing my greases I use acidic mixtures, consisting essentially ofrelatively high-molecular-weight carboxylic acids soluble in petroleumhydrocarbons but insoluble in water, which acidic mixtures are found inand may or may not be separated from reaction mixtures from the' partialoxidation of such hydrocarbon mixtures as 36-40" Baum petroleumdistillate,'45 Baum petroleum distillate, and other mineralhydrocarbons, including parafin wax, but especially the semi-solidproduct, known variously as dark green petrolatum, Sharples wax, oramorphous wax, which is obtainable from crude petroleum oil by dilutingthe topped crude with a relatively large amount of gasoline,

chilling the 'mixture to say to 40 below zero F., and centrifugingliquids from the so-chilled mass.

Thus, the starting material for the preparation of these soaps may bethe whole mass, resulting from the protracted oxidation of paramn wax,

or it may be an acidic mixture separated from solution described inMethod I above, is treated a saponification value of from about 110 toabout 1'75 or an acidic mixture separable therefrom or it may be anacidic mixture separable from the reaction mixture from the partialoxidation of one or another of the other mineral hydrocarbons referredto above.

The process of oxidation, which forms no part of the present invention,and the compositions of the resulting reaction mixtures, are fullydescribed in my U. S. Patent No. 1,768,523. These reaction mixturesconsist essentially of the aforesaid petroleum-solublehigh-molecular-weight saturated aliphatic carboxylic acids,unsaponiflable but readily emulsifiable oxygen-compounds of hydrocarbonsincluding compounds of alcoholic and/or ketonic constitutiomandunoxidized hydrocarbons, all in varying amounts. Preferably I oxidizeunder such conditions and for such a period of time that the reactionmixture has a saponification equivalent of from about 110 or 120 toabout 1'75.

From the aforesaid reaction mixtures I may, and preferably do, separatea product rich in, or substantially consisting of, the said aliphaticcarboxylic acids by one of a number of operable methods including thefollowing preferred methods:

I. Saponiflcation method To the reaction mixture is added sufficientsaponifying agent, e. g., caustic soda solution, to saponify all of thesaponiflable constituents thereof, the resulting soapy solution isseparated from oily, unsaponified and non-emulsified components of themixture, and the soapy solution is treated with an amount of an acid, e.g., sulphuric acid, sufficient to'decompose or break" the soapsprecipitating the water-insoluble organic compounds thereby released,and separating the precipitated organic compounds from the aqueoussolution; The organic compounds which constitute the separated mixtureconsist essentially of the aforesaid high-molecular-weight aliphaticcarboxylic acids together with a material amount ofunsaponifiable,non-acidic, oxidized hydrocarbons which readily emulsify with theaforesaid soaps and persistently associate with them.

II. Alcoholic separation method The aforesaid reaction mixture, or thesoapy with alcohol (e. g., to ethyl alcohol of constituents thereof, thealcoholic solution is.

separated from the constituents insoluble in alcohol, and the solvent isremoved (as by distillation) from the so-separated compounds. By thismethod a resulting product is obtainedwhich is considerably richer-in,or consists substantially of, the aforesaid acids.

By whichever of the above methods produced, the product rich in theaforesaid acids may readily be saponified by treatment with anappropriate amount, that is, the theoretical amount, of an alkalinesaponifying agent such as caustic soda to neutralize the acidicconstituents thereof, whereby to produce soaps (or neutral productsconsisting largely or essentially of soaps) of theacids, which soapmixture, or soapy mixture, is freely soluble in or miscible with thecommonly known and used lubricating oils or their equivalents to theproduction of lubricating greases having the desirable propertieshereinbefore de: scribed. 7

Illustrative of the manner in which the greases forming the basis of thepresent invention are prepared is the following:

Example I steam-refined lubricating oil stock (10 pounds),

and the dehydrated mixture is saponified by treatment with 14.4 poundsof a 50% caustic soda solution, either at room temperature or at anelevated temperature of the order of 200 F., with thorough stirring. Tothe dehydrated mixture there is then added, with agitation and while themixture is maintained at a temperature above about 220 R, an amount ofthe lubricating oil stock sufficient to bring the total content oflubricating oil to the proportion desired, say 40 pounds. I may, andpreferably do, subject the mixture to a milling treatment or itsequivalent to smooth out any lumps or granules in the grease product.The resulting composition is then drawn off into suitable molds or othercontainers and there solidified by cooling.

The above-described dehydration step is not essential and, of course, isnot practiced in the case where the acidic starting material containspractically no water.

The. lubricating grease so produced is a driving journal compound havinga melting point of about 540 F. but begins to deform at about 460-475"F.: it is much more unctious to the touch than a sodium stearate grease,is not sticky, and does not leak its lubricating oil constituent eitherin storage or under the conditions of use, breaks (cold) with aconchoidal fracture, and is slippery to the touch. .From the standpointof economy, it may be prepared at an actual cost materially below thatof the commonly used sodium stearate grease.

The foregoing specific example may be modified by the substitution of anacidic mixture separated from the reaction mixture produced by theoxidation of paraifin wax or of one or another of the variousdistillates of petroleum, or by the substitution of the acidic reactionmixtures as such, for the acidic mixture there specifically disclosed.As was indicated in the foregoing general description of the invention,I may subject the oxidized masses, as such, to saponification treatment,whereby to transform into soaps their whole content of saponiflableconstituents, there by producing a soapy product consisting of, on roil, in the manner described in the foregoing specific example, to theproduction of greases.

The relative consistency or hardness of the greases forming the basis ofthe present invention may be modified in any one of several ways:

scribed. Thus, there may be made in substantially the same mannerrelatively softer greases,

having lower. melting and deforming points, in-.

cluding cup greases, roller bearing greases,

'- greases adapted for use in lubricating floating bushing bearings, andthe like. Also, a relatively very hard grease may be prepared bycombining with the soap described in Example I above a suitable amount,say 40%, of unoxidized dark. green petrolatum or Sharples wax". Thislatpetroleum lubricating oil of about 200 viscosity (at 100 C.) with thesoap produced by treating with calcium hydroxide the acidic mixtureobtained from oxidized parafllne wax. This latter is a transparent,light-colored, grease of excellent lubricating properties.

The grease from the calcium soaps oi the petroleum acids" are preparedlna manner similar to that commonly employed in the making of limegreases" from stearic acid or tallow, it being desirable, however, onaccount of the tendency of the calcium' hydroxide to seize the petroleumacids" to mix a small amount oi lubricating oil stock with the acidsbefore adding the calcium hydroxide, and then to introduce the latterinto the mixture as an emulsion of the cal? cium hydroxide in a furtheramount of the lubricating oil: after the soap is well dispersed thenecessary further additions of lubricating oil may be made. Thisreaction preferably is conducted at a temperature below 212 F. and undervigorous agitation. The resulting products are remarkably unctious, ofshort shear, and of a more or less buttery consistency.

Example H A leaded transmission grease" may be prepared by the followingmethod:

The oxidation reaction mixtureohtained from Sharples wax is saponifiedin the manner set out in Example ll above, the soap solution isseparatedfrom unsaponiflable constituents or the reaction mixture and is largelydiluted with water whereby to precipitate emulsified but unsaponifiedbodies persisting with the soap solution, and the resulting purifiedsoap solution is treated with an appropriate amount of a lead salt,such, for instance, as lead nitrate, in aqueous solution. Thereby thereis precipitated a mixture of lead soaps of the acids, which mixture maybe dehydrated inknown manner. at about 245 to 265 F. These lead soapsare admixed without difficulty, in the warm, with a lubricating oilstock, producing what apparently is a true solution of the lead soaps inthe oil.

Instead of the above method, these lead soaps may be prepared bytreating the separated acidic mixtures with lead carbonate or anequivalent lead salt, or, with less facility, even litharge. In thelast-mentioned case, it is difllcult to dissolve or suspend suflicientlitharge in the acidic mixture to obtain as high a lead content in theresulting soap as is possible when practicing the --double-decompositionmethod above described.

My researches with other metallic soaps of these "petroleum acids" hasdemonstrated that the soaps of iron, aluminum, manganese and othermetals all are either soluble, or at least distensible, in lubricatingoils whereby to make lubricating greases. Furthermore, soda-limegreases, and other so-called mixed greases and "sett greases have beenmade in accordance with this process.

By the expression a salt of. a petroleum acid' as used in the appendedclaims I mean to include not only a" single salt of a single isolatedpetroleum acid but also either salts of a plurality oi'petro- Bypetroleum acid" as used in the appended claims I mean a relativelyhigh-molecular weight, saturated, aliphatic, carboxylic acid soluble inpetroleum but insoluble in water, which acid was derived from analiphatic hydrocarbon of mineral origin by controlled liquid-phasepartial oxidation of the latter. See the disclosures in U. S. Patents1,828,356, 1,863,004 and 1,770,876.

I claim:

1. Process which comprises treating with a saponifying agent arelatively high molecular weight saturated aliphatic petroleum acidderived from a reaction mixture obtained by the controlled partialoxidationloi a mixture of aliphatic petroleum hydrocarbons andincorporating in the resulting soap -a petroleum lubricating oil in anamount substantially greater than that of the soap but restricted to theproduction of a product which is solid-to semi-solid at normal roomtemperature. I

2. A lubricating grease composition consisting essentially of from about35 to about 50% by weight of a hydrocarbon mixture of mineral origin andhaving lubricating properties containing dissolved therein from about 65to about 50% by weight of oil-soluble salts of a mixture of relativelyhigh molecular weight saturated aliphatic carboxylic acids derived froman aliphatic hydrocarbon mixture oi mineral origin bycontrolledliquid-phase partial oxidation of the latter, said composition being asolid grease.

3. As a new product, a lubricating grease con-' sisting essentially of asubstantially anhydrous solution 01' a soap the acid radical of which isa saturated aliphatic carboxylic petroleum acid derived from a reactionmixture obtained by the controlled liquid phase partial oxidation of amixture of aliphatic petroleum hydrocarbons and the basic radical ofwhich is a metallic element or the group consisting of sodium,potassium, calcium, iron, aluminum, manganese and lead in asubstantially anhydrous medium consisting of a mineral lubricating oil,which grease is semisolid to solid at normal room temperature.

- 4. The product defined in claim 3 characterized in that the basicradical is sodium.

5. The product defined in claim 3 characterized in that the basicradical is calcium.

petroleum hydrocarbons rich in petroleum acids.

6. The product defined in claim 3 characterized oxidation of ,a mixtureof aliphatic petroleum hydrocarbons with a reactive compound of a metaloi the group consisting of sodium, potassium, calmixture obtained by thecontrolled liquid-phase cium, iron, aluminum, manganese and lead,partial oxidation of a mixture of aliphatic pewhereby a salt of saidmetal and said acid is troleum hydrocarbons with an alkalinesaponifyproduced and dispersing the so-iormed salt in a ing agent in anamount to neutralize the said acid petroleum lubricating oil in suchrelative proporwith formation of a soap therefrom, and dissolv- 5 tionsas to yield a product which is solid to semiing the so-formed soap in apetroleum lubricating solid at normal room temperature. oil in suchrelative proportions as to yield a prod- 8. Process which comprisesreacting a dehyuct which is solid to semi-solid at normal room dratedsodium soap of a saturated aliphatic cartemperature.

i boxylic petroleum acid derived from a reaction ARTHUR W. BURWEIL. 10-

